490 



Mr. R. Appleyar 



suddenly restored, the megohms rise once more to 18*5. It 

 is especially interesting to note that for small loads the 2nd 

 min. deflexion is always greater than the 1st min. deflexion, 

 whereas for loads from 119"8 to 90*8. in the order shown in 

 Table I., the 1 min. and 2 min. readings are at first equal, 

 then the first is greater than the second, and finally they 

 are again equal. The same general result will be noticed 

 in the tests with tin-foil electrodes, which follow. Increase 

 of voltage, as well as increase of the load, appears to have 

 the effect of improving the contact when contact is imperfect. 

 With small loads, it may be assumed that the surfaces are 

 partially out of contact, and that the effect of the current is 

 to improve the contact, so that the resistance diminishes, and 

 the deflexion increases. Meanwhile the normal effect of 

 " absorption " tends to produce an apparent increase in the 

 resistance, and a point is reached at which no change o£ 

 deflexion is observed, the effects being balanced. Finally, 

 with the greater load, the films are in more intimate contact 

 and the absorption effect preponderates, the second-minute 

 readme; being then less than the first-minute readme;. 



Experiment 2. — In order to examine the change in resist- 

 ance with change of voltage, using tinfoil electrodes, the 

 experiment represented by Table II. was carried out. The 

 dielectric was short-circuited for about one minute between 

 each change of voltage. 





Table II.— Ti 



nfoil Electrodes. 





Load in 

 grammes 



Volts. 



Shunt, 

 ohms. 



Deflexion, 

 1 min. 



Deflexion, 

 2 min. 



Megohms. 



per cm. 2 













22-3 



150 



2000 



272 



285 



310 



}) 



300 



600 



288 290 



202 





450 



500 



424 426 



17-3 



)( 



600 



300 



382 383 



15-7 



,, 



750 



2UU 341 342 



14-8 



" 



600 



300 386 386 



15-6 





450 



500 442 443 



16-6 





300 



600 



316 317 



18-4 



5) 



150 



2000 



344 1 347 



24-5 



5! 



750 



200 



336 



336 



150 





150 



2000 



342 



345 



24 6 



543 



150 



1000 



334 



334 



14-1 





31)0 



400 



306 



304 



130 



j> 



450 



300 



354 



352 



12-8 





600 



200 



325 



324 



12-5 



jj 



750 



140 



292 



291 



12-2 



J3 



600 



200 



326 



324 



12-4 



j) 



450 



300 



360 



356 



12-6 



>> 



300 



400 



308 



308 



12-9 



,, 



150 



3 000 



346 



345 



136 



>) 



750 



140 



292 2U0 



12-2 





150 



1000 348 347 



1 1 



135 



